/* OPENBSD ORIGINAL: lib/libc/net/inet_ntop.c */

/*	$OpenBSD: inet_ntop.c,v 1.5 2002/08/23 16:27:31 itojun Exp $	*/

/* Copyright (c) 1996 by Internet Software Consortium.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
* SOFTWARE.
*/

#include "winrtsock.h"

#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char rcsid[] = "$From: inet_ntop.c,v 8.7 1996/08/05 08:41:18 vixie Exp $";
#else
static char rcsid[] = "$OpenBSD: inet_ntop.c,v 1.5 2002/08/23 16:27:31 itojun Exp $";
#endif
#endif /* LIBC_SCCS and not lint */

#include <string.h>
#include <errno.h>
#include <stdio.h>

#ifndef IN6ADDRSZ
#define IN6ADDRSZ   16   /* IPv6 T_AAAA */                 
#endif

#ifndef INT16SZ
#define INT16SZ     2    /* for systems without 16-bit ints */
#endif

/*
* WARNING: Don't even consider trying to compile this on a system where
* sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
*/

#ifdef __cplusplus
extern "C" {
#endif
	static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
	static const char *inet_ntop6(const u_char *src, char *dst, size_t size);
#ifdef __cplusplus
}
#endif

/* char *
* inet_ntop(af, src, dst, size)
*      convert a network format address to presentation format.
* return:
*      pointer to presentation format address (`dst'), or NULL (see errno).
* author:
*      Paul Vixie, 1996.
*/
const char* inet_ntop(int af, const void *src, char *dst, size_t size)
{
	switch (af)
	{
	case AF_INET:
		return (inet_ntop4((u_char *)src, dst, size));
	case AF_INET6:
		return (inet_ntop6((u_char *)src, dst, size));
	default:
		errno = EAFNOSUPPORT;
		return (NULL);
	}
	/* NOTREACHED */
}

/* const char *
* inet_ntop4(src, dst, size)
*      format an IPv4 address, more or less like inet_ntoa()
* return:
*      `dst' (as a const)
* notes:
*      (1) uses no statics
*      (2) takes a u_char* not an in_addr as input
* author:
*      Paul Vixie, 1996.
*/
static const char *inet_ntop4(const u_char *src, char *dst, size_t size)
{
	static const char fmt[] = "%u.%u.%u.%u";
	char tmp[INET_ADDRSTRLEN];
	int l;

	l = sprintf_s(tmp, INET_ADDRSTRLEN, fmt, src[0], src[1], src[2], src[3]);
	if (l <= 0 || l >= (int)size)
	{
		errno = ENOSPC;
		return (NULL);
	}
	strcpy_s(dst, min(sizeof(tmp), size), tmp);
	return (dst);
}

/* const char *
* inet_ntop6(src, dst, size)
*      convert IPv6 binary address into presentation (printable) format
* author:
*      Paul Vixie, 1996.
*/
static const char *inet_ntop6(const u_char *src, char *dst, size_t size)
{
	/*
	* Note that int32_t and int16_t need only be "at least" large enough
	* to contain a value of the specified size.  On some systems, like
	* Crays, there is no such thing as an integer variable with 16 bits.
	* Keep this in mind if you think this function should have been coded
	* to use pointer overlays.  All the world's not a VAX.
	*/
	//char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
	char tmp[100], *tp;
	struct { int base, len; } best, cur;
	unsigned int words[IN6ADDRSZ / INT16SZ];
	int i;

	/*
	* Preprocess:
	*      Copy the input (bytewise) array into a wordwise array.
	*      Find the longest run of 0x00's in src[] for :: shorthanding.
	*/
	memset(words, '\0', sizeof words);
	for (i = 0; i < IN6ADDRSZ; i++)
		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
	best.base = -1;
	cur.base = -1;
	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
	{
		if (words[i] == 0)
		{
			if (cur.base == -1)
				cur.base = i, cur.len = 1;
			else
				cur.len++;
		}
		else
		{
			if (cur.base != -1)
			{
				if (best.base == -1 || cur.len > best.len)
					best = cur;
				cur.base = -1;
			}
		}
	}
	if (cur.base != -1)
	{
		if (best.base == -1 || cur.len > best.len)
			best = cur;
	}
	if (best.base != -1 && best.len < 2)
		best.base = -1;

	/*
	* Format the result.
	*/
	tp = tmp;
	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
	{
		/* Are we inside the best run of 0x00's? */
		if (best.base != -1 && i >= best.base &&
			i < (best.base + best.len))
		{
			if (i == best.base)
				*tp++ = ':';
			continue;
		}
		/* Are we following an initial run of 0x00s or any real hex? */
		if (i != 0)
			*tp++ = ':';
		/* Is this address an encapsulated IPv4? */
		if (i == 6 && best.base == 0 &&
			(best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
		{
			if (!inet_ntop4(src + 12, tp, sizeof tmp - (tp - tmp)))
				return (NULL);
			tp += strlen(tp);
			break;
		}
		tp += sprintf_s(tp, tp - tmp, "%x", words[i]);
	}
	/* Was it a trailing run of 0x00's? */
	if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
		*tp++ = ':';
	*tp++ = '\0';

	/*
	* Check for overflow, copy, and we're done.
	*/
	if ((size_t)(tp - tmp) > size)
	{
		errno = ENOSPC;
		return (NULL);
	}
	strcpy_s(dst, min(sizeof(tmp), size), tmp);
	return (dst);
}
